This invention relates to a dehydration method for efficiently removing water contained in foods such as fish, meat, vegetables, fruits, crops, and processed products thereof and to a dehydration system to be used therefor, and more specifically to a dehydration method that can remove water from a large amount of materials continuously.
Water contained in foods such as fish, meat, vegetables, fruits, and processed products thereof (hereinafter simply referred to as "foods") may be a cause of deterioration in the quality of foods deteriorated freshness, freezing damage, occurrence of dripping at thawing. Therefore, a variety of methods have been proposed for removing water contained in foods.
For example, Japanese Patent Publication No. 58124/1983 and U.S. Pat. No. 4,383,376 disclose a method in which foods are wrapped in a special sheet material based on a combination of a high-osmotic-pressure material and a semipermeable membrane to remove water therefrom. However, the method has been defective in that it requires a substantial cost and time for the manufacture of the special sheet material, the foods must be individually wrapped in the sheet material and the individual food packages are separately subjected to dehydration. Accordingly this method results in extremely low efficiency, and it is not adaptable for automation.
Japanese Patent Application (Laid-open No. 187759/1984) describes a method in which foods, which are sliced as needed, are dipped in a dehydrating solution comprising a sugar solution alone or its mixture to absorb water contained in the foods into the dehydrating solution, using a difference in osmotic pressure between the dehydrating solution and foods. However, this method has a problem in that the dehydrating solution containing sugar and other substances may permeate the foods, which can result in a change in the original taste and flavor of the foods. Further, since as the dehydrating solution absorbs water from the foods, its concentration varies with time, it is difficult to treat a large amount of foods with the same dehydrating solution for an extended period of time.